Medical and Healthcare Professions: Medical Doctors: Physiology forms the foundation for medical education. It is essential for diagnosing, treating, and preventing diseases. Doctors need a deep understanding of how the body's systems work to provide effective patient care. Nurses: Nurses rely on physiology to monitor patients' vital signs, administer medications, and provide overall care. Understanding physiology is vital for patient safety. Pharmacists: Pharmacists require knowledge of physiology to understand drug interactions, mechanisms of action, and potential side effects. Biomedical Research: Physiologists and researchers use knowledge of physiology to conduct experiments, develop new therapies, and advance medical science. This research is critical for discovering treatments for diseases. Sports Science and Exercise Physiology: Understanding how the body responds to exercise and physical activity is essential in sports science. Coaches, athletes, and fitness professionals rely on this knowledge to optimize training regimens and improve performance. Nutrition and Dietetics: Nutritionists and dietitians use physiology to understand how nutrients affect the body's various systems. This knowledge helps in designing diets to manage health conditions and promote overall well-being. Pharmaceutical and Biotechnology Industries: Professionals in these industries need to understand the physiological effects of drugs and biotechnological products to develop safe and effective treatments. Biomechanics: Physiological principles are fundamental in biomechanics, which is crucial in fields like orthopedics, physical therapy, and engineering to design prosthetics and improve mobility. Environmental Science: Environmental scientists study the physiological responses of organisms to changes in their environment, which is essential for understanding the impact of climate change and pollution on ecosystems. Psychology and Neurobiology: Understanding the physiological basis of behavior and cognition is critical in psychology and neuroscience. This knowledge helps in researching and treating mental health disorders. Public Health: Public health professionals need to comprehend the physiological aspects of disease transmission and prevention, especially in epidemiology and health policy development. Education and Science Communication: Educators and science communicators use physiology to teach students and the general public about the importance of health and wellness, disease prevention, and medical advancements. Personal Well-Being: Knowledge of physiology helps individuals make informed decisions about their health, leading to a healthier lifestyle, better disease prevention, and improved quality of life. In summary, the study of physiology is a cornerstone of various disciplines and professions, impacting healthcare, research, sports, nutrition, industry, and more. It equips students with a deep understanding of how the human body functions, en

1. TOPIC: DERMAL TOXICITY
STUDIES AS PER OECD
GUIDELINES
PRESENTED BY: Vaishnavi Patel
ID NUMBER: 22 PHPG059009
Mpharm (Semester II)
SUBJECT NAME: Pharmacological and toxicological screening methods- II

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LEARNING OUTCOMES
INTRODUCTION
PRINCIPLE OF IN VIVO TEST
PREPARATION OF THE IN VIVO TEST
TEST PROCEDURE
OBSERVATION STUDIES
DATA AND TEST REPORTING

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INTRODUCTION
The testing strategy includes
the performance of validated
and accepted in vitro tests and
is provided as a Supplement to
this Guideline.
In addition, where appropriate,
the successive, instead of
simultaneous, application of
the three test patches to the
animal in the initial in vivo test
is recommended in this
Guideline.

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For new substances it is the recommended stepwise testing approach for developing
scientifically sound data on the corrosivity/irritation of the substance.
The strategy should be used for existing substances with insufficient data on dermal
corrosion/irritation to fill missing data gaps. Significant deviation from the testing strategy or
procedure, or a decision not to use a stepwise testing approach, should be justified.

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PRINCIPLE OF THE IN VIVO TEST
The substance to be tested is applied in a single
dose to the skin of an experimental animal;
untreated skin areas of the test animal serve as
the control.
The degree of irritation/corrosion is read and
scored at specified intervals and is further
described in order to provide a complete
evaluation of the effects.
The duration of the study should be sufficient to
evaluate the reversibility or irreversibility of the
effects observed.

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• Animals showing continuing signs of severe distress and/or pain at
any stage of the test should be humanely killed, and the substance
assessed accordingly.
• Criteria for making the decision to humanely kill moribund and
severely suffering animals are the subject of a separate Guidance
Document

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PREPARATIONS FOR THE IN VIVO TEST
Selection of animal species
• The albino rabbit is the preferable laboratory animal, and
healthy young adult rabbits are used. A rationale for
using other species should be provided.
Preparation of the animals
• Approximately 24 hours before the test, fur should be
removed by closely clipping the dorsal area of the trunk
of the animals.
• Care should be taken to avoid abrading the skin, and only
animals with healthy, intact skin should be used.
• Some strains of rabbits have dense patches of hair that
are more prominent at certain times of the year. Such
areas of dense hair growth should not be used as test
sites.

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Housing and feeding
conditions
• Animals should be individually housed.
• The temperature of the experimental animal
room should be 20°C (± 3°C) for rabbits.
• Humidity should be at least 30% and preferably
not exceed 70%, other than during room
cleaning, the aim should be 50-60%.
• Lighting should be artificial, the sequence being
12 hours light, 12 hours dark.
• For feeding, conventional laboratory diets may
be used with an unrestricted supply of drinking
water.

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TEST PROCEDURE
• Application of the test substance 12. The test substance should
be applied to a small area (approximately 6 cm2 ) of skin and
covered with a gauze patch, which is held in place with non-
irritating tape.
• In cases in which direct application is not possible (e.g., liquids
or some pastes), the test substance should first be applied to
the gauze patch, which is then applied to the skin.
• The patch should be loosely held in contact with the skin by
means of a suitable semi-occlusive dressing for the duration of
the exposure period.
• If the test substance is applied to the patch, it should be
attached to the skin in such a manner that there is good
contact and uniform distribution of the substance on the skin.
• Access by the animal to the patch and ingestion or inhalation
of the test substance should be prevented.

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DOSE LEVEL
A dose of 0.5 mL of liquid or 0.5 g of solid or paste is applied to the test site.
Initial test (in vivo dermal irritation/corrosion test using one animal)
If a corrosive effect is observed after any of the three sequential exposures, the test is
immediately terminated. If a corrosive effect is not observed after the last patch is removed,
the animal is observed for 14 days, unless corrosion develops at an earlier time point

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Confirmatory test (in vivo
dermal irritation test with
additional animals)
• If a corrosive effect is not observed in the initial
test, the irritant or negative response should be
confirmed using up to two additional animals,
each with one patch, for an exposure period of
four hours.
• If an irritant effect is observed in the initial test,
the confirmatory test may be conducted in a
sequential manner, or by exposing two
additional animals simultaneously..

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• In the exceptional case, in which
the initial test is not conducted,
two or three animals may be
treated with a single patch, which
is removed after four hours.
• When two animals are used, if
both exhibit the same response,
no further testing is needed.
• Otherwise, the third animal is also
tested. Equivocal responses may
need to be evaluated using
additional animals

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Observation period
The duration of the observation
period should be sufficient to
evaluate fully the reversibility of
the effects observed.
However, the experiment should
be terminated at any time that
the animal shows continuing
signs of severe pain or distress.
To determine the reversibility of
effects, the animals should be
observed up to 14 days after
removal of the patches.
If reversibility is seen before 14
days, the experiment should be
terminated at that time.

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Clinical observations and grading of skin reactions
All animals should be examined for signs of erythema
and edema, and the responses scored at 60 minutes,
and then at 24, 48, and 72 hours after patch removal.
For the initial test in one animal, the test site is also
examined immediately after the patch has been
removed. Dermal reactions are graded and recorded
according to the grades in the Table below.
If there is damage to skin that cannot be identified as
irritation or corrosion at 72 hours, observations may be
needed until day 14 to determine the reversibility of
the effects. In addition to the observation of irritation,
all local toxic effects, such as defatting of the skin, and
any systemic adverse effects (e.g., effects on clinical
signs of toxicity and body weight), should be fully
described and recorded.
Histopathological examination should be considered to
clarify equivocal responses.

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DATA AND REPORTING
Evaluation of results:
• The dermal irritation scores should be evaluated in
conjunction with the nature and severity of
lesions, and their reversibility or lack of
reversibility.
• Reversibility of dermal lesions should be
considered in evaluating irritant responses. When
responses such as alopecia (limited area),
hyperkeratosis, hyperplasia and scaling, persist to
the end of the 14-day observation period, the test
substance should be considered an irritant.

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TEST REPORT
• description of relevant data
available from prior testing;
• data derived at each stage of
testing strategy;
• description of in vitro tests
performed, including details of
procedures, results obtained
with test/reference substances;
• weight-of-the-evidence analysis
for performing in vivo study.

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Test substance: -
• identification data (e.g. CAS number; source;
purity; known impurities; lot number)
• physical nature and physicochemical
properties (e.g. pH, volatility, solubility,
stability);
• if mixture, composition and relative
percentages of components.

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Vehicle:
• Identification, concentration (where appropriate),
volume used;
• Justification for choice of vehicle.
Test animals:
• Species/strain used, the rationale for using animals
other than an albino rabbit;
• number of animals of each sex;
• individual animal weights at the start and conclusion
of the test;
• age at the start of the study;
• source of animals, housing conditions, diet, etc.

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Test conditions:
• Technique of patch site preparation;
• Details of patch materials used and patching
technique;
• Details of test substance preparation,
application, and removal.

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Results:
tabulation of irritation/corrosion response scores
for each animal at all time points measured;
• descriptions of all lesions observed;
• narrative description of nature and degree of
irritation or corrosion observed, and any
histopathological findings;
• description of other adverse local (e.g., defatting
of skin) and systemic effects in addition to
dermal irritation or corrosion.

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